foc MODIS | R-bloggeri

16 noiembrie 2025

Obțineți fișiere pentru tot anul 2024 disponibile în /data/MODIS/C61/MCD14ML.

Vom folosi binning pe o rețea globală discretă de 250 km.

# countries background
world <- ne_countries(scale = 10) |> 
  st_make_valid() |> 
  st_wrap_dateline()

# build the grid
dggs <- dgconstruct(spacing = 250) 

hex <- dggs |> 
  dgshptogrid(world, cellsize = 0.5) |> 
  st_make_valid() |>
  st_wrap_dateline() |> 
  st_filter(world) |> 
  select(seqnum)

# read all MODIS files and find their grid cell ID
modis <- dir("~/data/modis/", full.names = TRUE) |> 
  read_fwf(
    skip = 1,
    col_types = cols("YYYYMMDD" = col_date(format = "%Y%m%d")),
    fwf_positions(
      c(1, 10, 15, 17, 26, 36, 42, 48, 53, 61, 65, 68),
      c(9, 14, 16, 25, 35, 41, 47, 52, 60, 64, 67, 69),
      c("YYYYMMDD", "HHMM", "sat", "lat", "lon", "T21", "T31", "sample", "FRP", 
        "conf", "type", "dn")),
    num_threads = 10) |> 
  mutate(seqnum = dgGEO_to_SEQNUM(dggs, lon, lat)$seqnum)